AcademicArticleSCO_85032925883

abstract

• © Copyright 2016, Mary Ann Liebert, Inc. Intensive use of organophosphorus pesticides (OPs) leads to their accumulation in most compartments of the environment, creating an issue of international concern that demands development and implementation of analytical methods for the assessment of environment quality. Official protocols require the use of sophisticated instruments, such as high performance liquid chromatography-mass spectrometry or gas chromatography/mass spectrometry, for the accurate and sensitive determination of OPs; however, methods based on these techniques are inconvenient for routine analysis of large numbers of samples or on-site analysis. Therefore, simple and fast alternative methods for the determination of OPs are needed. In this work, a colorimetric assay based on decrease in catalytic activity of chloroperoxidase (CPO) enzyme has been developed for the detection and quantification of OPs. Decrease in standard catalytic activity of CPO (halogenation of thionin acetate) was due to competition by OPs for the enzyme's active site, which affected CPO kinetic constants. Consequently, a correlation was observed between concentration of OPs and decrease in CPO catalytic activity, enabling indirect determination of OPs in water samples. The proposed method demonstrated mean recoveries between 92.3% and 106.5%, with a measuring time of 20 s per sample. The enzymatic analytical method was applied to groundwater samples. Performance of the developed assay is comparable to that of commercial assay kits based on the enzyme acetylcholinesterase, but has a shorter analysis time and does not require a preoxidation step. Therefore, this approach constitutes a sensitive, fast, and high-throughput method for OPs screening in aquatic environments.